I have seen some crazy consumptions on vehicles as well, most are due to mechanical defects since I usually talk with people whom have older vehicles. To my understanding it is considered "normal" for a vehicle to use 1 quart/1,000 miles, correct? If vehicle manufacturer's are aware of this and consider it "safe" and "normal" then that should mean that the oil burning would not poison the catalytic converter. Note, "should," and "if-then" are the keywords there. Just to clear it up, I never once said that phosphorous would never cause catalytic failure, what I am saying is that for some reason the first thing that people go for with Amsoil is "it'll poison the cat because of 'too much' phosphorous." I can definitely see phosphorous, regardless of oil type or brand, causing catalytic poisoning if there is an abnormal amount of oil consumption.